This invention relates to a process for the production of flame-retardant polyurethane foams wherein the blowing agent is produced by the chemical reaction of the flame-retardant compound with the polyisocyanate compound thereby producing a stable foam. No additional blowing agents are necessary.
The production of polyurethane products is well known in the Arts and many types of flame-retardant chemicals have been used in the process. The novel part of this invention is the utilization of the blowing agent produced by the reaction of the flame-retardant agent with the polyisocyanate compound to produce the foamed polyurethane products. It is not necessary to add another blowing agent such as freon-in order to produce a stable foamed product. The elimination of the need to use halogenated blowing agents in polyurethane foams will be beneficial to mankind. In the process of this invention, low cost and readily available compounds are utilized and there is an improvement in the cost of the product because expensive blowing agents are not needed.
While not wishing to be bound by any theory of operation, it appears that carbon dioxide and/or a gaseous alkyl compound is produced in the reaction and carbon dioxide is probably released from the polyisocyanate when it reacts with an organic phosphorus containing compound. The organic phosphorus containing compound also acts as the flame-retardant agent. The reaction between polyisocyanate and the organic phosphorus containing compound is enhanced by the addition of a polyurethane catalyst, especially the organic tin catalyst. In this reaction the gaseous compound is produced at a rate wherein the reacting components expand at a normal rate and solidifies at the end of the expansion to produce a flame-retardant polyurethane foamed product which may contain open and/or closed cells.